Electronic governor for automotive automatic transmission

ABSTRACT

A control device for electronically controlling the gear shifts in an automotive automatic transmission in response to changes in the vehicle speed and in the displacement of the accelerator pedal. Signals are produced representing the changes at any given time in the vehicle speed and position of the accelerator pedal to raise the gear shifting point to higher vehicle side particularly when the vehicle is running on an ascent or descent or when the engine is operating at a low temperature.

United States Patent 1 Mori [ 1 May 15,1973

1541 ELECTRONIC GOVERNOR FOR AUTOMOTIVE AUTOMATIC TRANSMISSION [75] Inventor: Yoichi Mori, Yokohama, Japan [73] Assignee: Nissan Motor Company, Limited, Kanagawa-ku, Yokohama City, Japan [22] Filed: Jan. 26, 1972 [21] App]. No.: 220,971

Related US. Application Data [63] Continuation-in-part of Ser. No. 872,124, Oct. 29,

1967, abandoned.

Tsurami-ku,

[30] Foreign Application Priority Data Oct. 30, 1968 Japan ..43/78835 [52] US. Cl ..74/866 [51] Int. Cl. ..B60k 21/02 [58] Field of Search ..74/866 [56] References Cited UNITED STATES PATENTS 3,019,666 1/1962 Brennan et a1. ..74/866 3,068,715 12/1962 Brennan et a1. .....74/866 X 3,267,762 8/1966 Reval ..74/866 X 3,354,744 11/1967 Kuhnle et a1. 74/866 X 3,433,101 3/1969 Scholl et a1 ..74/866 3,448,640 6/1969 Nelson ..74/866 Primary ExaminerCharles J. Myhre Assistant ExgrninerThomas C. Perry Attorney-John Lezdey [57] ABSTRACT A control device for electronically controlling the gear shifts in an automotive automatic transmission in response to changes in the vehicle speed and in the displacement of the accelerator pedal. Signals are produced representing the changes at any given time in the vehicle speed and position of the accelerator pedal to raise the gear shifting point to higher vehicle side particularly when the vehicle is running on an ascent or descent or when the engine is operating at a low temperature.

4 Claims, 18 Drawing Figures Pmmninmnsma SHEET mm m INVENTOR ymm Mm Y E W m w A PATENTEUHAY I 51975 sum 02 HF 1 INVENTOR ATTORNEY PATENTEUMAY 1 stars sum 03 HF 16 INVENTOR WNW Mme ATTORNEY IPATENTEUHAY 1 sma saw on 0F I6 INVENTOR ATTUR NEY PATENTEBHAY 1 5197s- Y'SHEET' 06 [1F 16 INVENTOR ATTORNEY PATENTED um S19v5 SHEET 07 0F 1 INVENTOR 'yelcm MM! ATTORNEY PATENTED am 5 ma 'SHEET 08 0F 16 INVENTOR YATTORNEY PATENTED WW1 9 3 SHEET 09 OF 1 6 INVENTOR ATTORNEY PATENTED MAY 1 5 \975 sum 13 0F 15 PATENTEDHATTEISB 7 ,7 ,754

. SHEET 1n 0F 16 KICK- DOWN I I SIGNAL FOR HIGH LOAD T CONDITION 0 L FOR NORMAL F5 HISGENLSSD r CONDITION g I KICK-DOWN SIGNAL 5 5 ACCELERATOR O DISPLACEMENT ANTI-CREEP SIGNAL SIGNAL 0 55 54 53 52 VEHICLE SPEED OUTPUT VOLTAGE PATENTEDMAH 5191a sum 15 or 1 Qmmmw mjufw :10 mawaav'lds PAIENIEBW 1 m sum 16 HF 1 ELECTRONIC GOVERNOR FOR AUTOMOTIVE AUTOMATIC TRANSMISSION This is a continuation-in-part application of the application Ser. No. 872,124 filed on Oct. 29, l969,'now abandoned.

The present invention relates to a control device for electronically controlling the gear shifts in an automatic transmission, and more particularly to a control device used as a governor for electronically controlling the shifting points of an automatic transmission for various driving conditions in accordance with vehicle speed by using a tachometric generator connected to the output shaft of the vehicle and with the displacement of the accelerator pedal by using a variable resis tor element.

The conventional governor is controlled merely by the vehicle speed and displacement of the accelerator pedal for determining the shifting points of an automatic transmission. This invites a serious lack of sufficient engine torque or braking effect by the engine particularly when the vehicle is going uphill with insufficient engine torque as a result of premature upshifting, or when itis going downhill with insufficient braking effect as a result of late downshifting due to early shifting, or when it is running down on a descent with no engine brake applied, or when the engine temperature is not high enough.

In order to overcome these and other disadvantages that are inherent in the conventional governor and to offer increased reliability of the gear shifting performance of the governor or control device, the present invention contemplates to provide a novel and improved control device of the type which is adapted to raise the shifting point to the higher vehicle speed side especially when the automobile is ascending or descending or when the engine temperature thereof is low during warming-up operation.

The features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a connection diagram showing the circuit arrangement of a control device as constructed according to the present invention,'the arrangement being shown to be in its neutral condition;

FIG. 2 is similar to FIG. 1, but shows the condition in which the first or low speed is selected;

FIG. 3 is similar to FIG. 1, but shows the condition in which the second or intermediate speed is selected;

FIG. 4 is similar to FIG. I, but shows the condition in which the third or high speed is selected;

FIG. 5 is a graphical representation of resultant shifting patterns plotted against the vehicle speed'and depression of the accelerator;

FIG. 6 is similar to FIG. 1, but shows the condition in which the kick-down operation is effected;

FIG. 7 is similar to FIG. 1, but shows the condition in which the high load operation is effected with the shifting point raised to higher vehicle speed;

FIG. 8 is similar to FIG. 5, but shows the shifting pattern obtained for the high load operation shown in FIG.

FIG. 9 is similar to FIG. 1, but shows the condition in which the low-hold operation is effected indifferently of the accelerator displacement with the shifting point lowered;

FIG. 10 is similar to FIG. 1, but shows the condition in which the vehicle runs on a level road with reduced accelerator displacement;

FIG. 11 is a block diagram showing the general concept of the present invention;

FIG. 12 is a block diagram showing the control device of the invention as shown in FIGS. 1 to 4, 5, 7, 9 and 10;

FIG. 13 is similar to FIG. 4, but shows another embodiment of the control device;

FIG. 14 is a graphical representation of an output voltage of an accelerator displacement detector or variable resistor element against the displacement of the accelerator pedal;

FIG. 15 is also a graphical representation of an output voltage of a vehicle speed detector or tachometric generator against the vehicle speed;

FIG. 16 is a graphical representation of resultant shifting patterns obtained when the low-hold operation is effected; and

FIG. 17 is similar to FIG. 4, but shows still another embodiment of the control device.

Referring now to FIG. l, the control device according to this invention comprises a dc. power source or storage battery 10, a voltage generator means having vechicle speed detector or tachometric generator 11 connected to a driven or output shaft of the vehicle such as the wheel axle and bridge rectifier, an accelerator displacement detector or variable resistor means element 12 for producing a signal voltage corresponding to the displacement of an accelerator pedal 13 which may control the position of the throttle valve (not shown) in the vehicle engine and which may be mechanically linked with a wiper arm 14 of the variable resistor element 12, two PNP transistors 15 and 16 acting as driving circuits for determining the shifting points between the first or low and the second or intermediate speeds, and between the second or intermediate andthe third or high speeds, respectively, first and second solenoids 17 and 18 for switching the delivery of the speed shifting signals when energized by the current flowing through collectors I9 and 20 of the transistors l5 and 16, respectively, so that relays 21, 22 and 23, 24 are switched on and off, respectively, by the solenoids l7 and 18.

In order to provide a proper accelerator displacement signal, there are provided resistor elements 25, 26, 27, 28 and 29, which resistors are all in series with each other and connected between the positive and negative terminals of the storage battery 10.

There are also provided in series resistor elements 30, 31, 32 and 33 for setting the potential of a base 34 of the transistor 15, and also provided in series resistor elements 35, 36, 37 and 38 for setting the potential of a base 39 of the transistor 16.

This control device also comprises a power switch 40 for switching on and off the dc. potential from the storage battery 10 to the variable resistor element 12.

According to an important feature of the invention, there is provided a switch 41 which changes the shifting patterns to a high speed side so as to make, when it is open, the shifting points suitable for the high load condition, when the vehicle is on an ascent, when an efficient braking effect by the engine is required or when the engine is operating at a low temperature. In other words, the switch 41 is adapted to produce a high load signal. Switches 42 and 43, when actuated, hold the low speed range in the transmission so that the potential of a circuit line 44 is set merely by the resistor element 25 and variable resistor element 45. This means that the switches 42 and 43 can produce a low-hold signal.

This device further comprises emitter resistor elements 46 and 47 for setting the current flowing through the transistors 15 and 16, respectively.

In order to protect the transistors 15 and 16 against overcurrent, diodes 48 and 49 are connected in parallel with the solenoids 17 and 18, respectively, in the collector circuits of the transistors 15 and 16.

The storage battery supplies voltage Va through a line 50 and a grounded line 51. The variable resistor element 12 includes, as' shown, a plurality of sliding contacts 52, 53, 54 and 55 spaced from each other. The positive terminal of the battery 10 is connected with the switch 41 and resistor elements 29, 45, 46 and 47 through a grounded line 56. This terminal is also connected with rectifying elements 57 and 58 connected in parallel with rectifying elements 59 and 60 connected in series with the elements 57 and 58, respectively. These rectifying elements 57 to 60 are all connected with the output of the tachometric generator 11 to supply a dc voltage which is proportional to the driven shaft speed of the vehicle. A reference voltage Vb is built up by the resistor element 25, switch 42, variable resistor element 12, resistor element 26, contact 53, resistor element 27, contact 54, resistor element 28, sliding contact 55, and switch 41 connected to the circuit line 50 and 56, which reference voltage Vb is fed to the bases 34 and 39 of the transistors and 16, respectively. The tachometric generator 11 generates a voltage proportional to the revolution speed of the driven shaft (which may actually be the wheel axle). The voltage is rectified by the rectifying elements 57, 58, 59 and 60 connected in a bridge form to provide a reference voltage Vs which is also fed to the bases 34 and 39 of the transistors 15 and 16. The resistor element 30, variable resistor element 31, resistor element 32 and variable resistor element 33 connected to the line 44 having the voltage Vb and a line 61 having the voltage Vs build up a reference voltage Vc which is applied directly to the base 34 of the transistor 15. The resistor element 35, variable resistor element 36, resistor elements 37 and 38, connected to the lines 44 and 61, establish a reference voltage Vd which is also fed directly to the base 39 of the transistor 16. The transistor 15 includes an emitter 62 connected through the resistor element 46 to the line 56 and a collector 19 connected through the solenoid 17 and diode 48 in parallel to the bus line 50. The transistor 16, similarly, includes an emitter 64 connected through the resistor element 47 to the line 56 and a collector connected through the solenoid 18 and diode 49 in parallel to the line 50.

In operation, when the power switch 40 is closed as shown in FIG. 2, the negative voltage Va is applied to the line 50. If, now, the accelerator pedal 13 of the vehicle is depressed, the wiper arm 14 of the variable resistor element 12 turns clockwise from the position seen in FIG. 1 so that a negative voltage Vb is applied through the arm 14 to the line 44.

Since the tachometric generator 11 does not operate when the vehicle stands still, the voltage Vs across the line 61 is zero so that a negative voltages Vc and Vd are applied through the resistor elements 30, 31, 32 and 33 to the base 34 of the transistor element 15 and through the resistor elements 35, 36, 37 and 38 to the base 39 of the transistor 16, respectively. Thus, the current flows through the emitter 62 and collector 19 of the transistor 15 and the solenoid 17 and also through the emitter 64 and collector 20 of the transistor 16 and the solenoid 18. The arms 66, 67 and 68, 69 of the relay switches 21, 22 and 23, 24, respectively, are moved to the opposite side as seen in FIG. 2 so that the first signal current for establishing the first speed flows to a line 70.

When the vehicle starts to move, the tachometric generator 11 generates a positive voltage so that the positive voltage Vs rectified by the rectifying means 57, 58, 59 and 60 is passed to the line 61 as shown in FIG. 3. As the vehicle speed further increases, the voltage Vs increases so that the voltages Vc and Vd fed to the bases 34 and 39 of the transistors 15 and 16 increase toward the positive. If the voltage Va is preset to exceed zero before the voltage Vd does, the transistor 15 becomes nonconducting so that the solenoid 17 is deenergized. This causes the arms 66 and 67 of the relay switches 21 and 22, respectively, to be switched to the positions seen in FIG. 3. Thus, the second signal current for selecting the second speed flows to a line 71.

Referring to FIG. 4, when the vehicle is accelerated further, the tachometric generator 11 generates a higher positive voltage so that an increased voltage Vs rectified by the rectifying elements 57, 58, 59 and 60 is applied to the line 61, whereupon the voltage Vd also exceeds zero. Thus, the transistor 16 also becomes nonconducting so that the solenoid 18 is de-energized to cause the arms 68 and 69 to be switched to the position indicated in FIG. 4. The third signal current for selecting the third speed flows to the conductor 72, consequently.

In order to further clarify the aforementioned operation of the present circuit, the potentials of the reference voltages Va, Vb, V0 and Vd at the respective operation will be calculated hereinafter.

If the resistance 27 is divided by resistances 73 and 74 by means of the arm 14. The voltage Vb when the switch 41 is closed and the switches 42 and 43 held in positions shown in FIG. 4, will be expressed as follows:

Vb1= -Va Similarly, when the arm 14 is on the contacts 54 and 55, respectively, voltages Vb and Vb are expressed as follows:

Vb Va iii-mi.)

Vb O

If a voltage Vb is a voltage Vb when the switch 41 contacts 52, 53, 54 and 55, respectively these voltages are expressed as:

22 21 2s)/( 25 R28 21 29) Va aa 24 es/( 25 R26 21 29) Va If, furthermore a voltage Vb is the voltage Vb when the switches 42 and 43 are shifted to the positions as seen in FIG. 4, the voltage Vb; is:

If voltages Vc, and Vc to appear as the voltage Vc when the current flows through the transistors and 16, namely, if the arms 67 and 69 of the contacts of the relay 21 and 23, respectively, are shifted to the opposite positions seen in FIG. 4, they are expressed as:

If the voltages Vd, and Vd 2 are to appear as the voltage Vd when the current is absent in the transistors 15 and 16, namely, if the arms 67 and 69, respectively, are shifted to the positions side as seen in FIG. 4, these voltages are:

In all these equations, it is assumed that the resistance 31 is divided by the arm 75 into resistances 76 and 77 and that the resistance 36 is divided by the arm 78 into resistances 79 and 80.

Referring to FIG. 5, the displacement of the accelerator 13 is indicated in terms of percentage. Here, it is assumed that the vehicle is running on a level road and that the switch 41 is closed to maintain the voltage across the line 44 at Vb In this instance, the wiper arm 14 is connected through a linkage designated by 81 to the accelerator pedal 13.

When the vehicle stands still so that the arm 14 of the variable resistor element 12 is on the contact 55 as illustrated in FIG. 1, the reference voltage Vs is equal to zero. Since the arm 14 is held on the sliding contact 55 of the element 12, the voltage Vb previously described is also equal to zero. This state of the operation of the transmission is indicated at point r in FIG. 5. The reference voltages Vc and Vd are also equal to zero. In this state of the circuit connection, since the collector current is absent in the respective transistors 15 and 16,

solenoids l7 and 18 remain de-energized so that the arms 66, 67 and 68, 69, respectively, are moved to the positions shown in FIG. 1. As the consequence, the third speed signals are delivered from the line 72 to the control system of the transmission (not shown). Thus, the switch 41 can produce an anti-creep signal, when it is closed, because the automatic transmission is in the third speed with the lowest engine torque while the vehicle stands still.

When the accelerator pedal 13 is depressed while the vehicle is stopped, the arm 14 of the element 12 shifted to the contact 54 as shown in FIG. 2. With this arm 14 held on the contact 54, the reference voltage Vb corresponds to the voltage Vb as previously calculated. This state of the operation is indicated at point z in FIG. 5. In this state, the voltages V0 and Vd become negative since the voltage Vb is negative so that the collector current flows through both the transistors l5 and 16, thereby to cause the arms 66, 67 and 68, 69, respectively, to be shifted to the positions shown in FIG. 2. Thus, the first speed signal is fed from the line 70 to the control circuit of the transmission (not shown).

When the accelerator pedal 13 is further depressed to such an extent as to correspond to the point s in FIG. 4 5, the vehicle starts to move so that tachometric generator 11 rotates and produces a positive reference voltage Vs which is fed through the rectifying elements 57, 58, 59 and to the circuit line 61. As the speed increases, the potential of the reference voltage Vs rises so that the voltages Vc and Vd increase from the negative to zero. When the pedal 13 is pressed to such an extent as to correspond with the point s in'FIG. 5, the

- reference voltage Vbis expressed as the Vb as previously noted. The voltages V0 and Vd are also represented by the Vc, and Vd respectively, as previously calculated. When the vehicle speed increases to the point y in FIG. 5, the reference voltage Vc, exceeds zero-to render the transistor 15 nonconducting thereby to cut off the current from the solenoid 17. The arms 21 and 22 are then switched over to the positions shown in FIG. 3. Thus, the second speed signal is delivered from the relay switch 21 through a line 82, relay 

1. A control device for electrically controlling gear shifts of an automatic transmission of an automotive vehicle as a function of vehicle speed and displacement of an accelerator pedal, comprising: accelerator displacement detecting means for detecting displacement of the accelerator pedal to produce an accelerator displacement signal having a voltage substantially proportional to said displacement; kickdown means provided in said accelerator displacement means for producing a kickdown signal having a voltage stepwise changed from said accelerator displacement signal; switch means connected with said accelerator displacement detecting means for producing a high load signal having a voltage higher than said accelerator displacement signal when closed and for producing an anit-creep signal having a zero potential when being open while the vehicle stands still; switch means for selectively permitting therethrough said accelerator displacement signal, kickdown signal and anti-creep signal and for selectively permitting therethrough a low-hold signal having a constant voltage; vehicle speed detecting means for detecting vehicle speed to produce a vehicle speed signal having a voltage substantially proportional to said vehicle speed, said vehicle speed signal being of polarity opposite to that of said accelerator displacement signal and kickdown signal; at least one comparating means receptive of said vehicle speed signal and any of said accelerator displacement, kickdown, high load, anti-creep and low-hold signals selected for comparing the voltages of said vehicle speed and said any signal; at least onE corresponding driving circuit connected with said comparing means for being rendered conductive when the compared voltages exceed their threshold values; and at least one corresponding relay means for being actuated by said driving means when it is energized to produce at their terminals a plurality of speed signals having a constant voltage, said speed signals being delivered to an electric circuit of an automatic transmission to effect a gear shift in accordance with the speed signals produced.
 2. A control device according to claim 1, further comprising at least one hysterisis feedback circuit for stepwise changing the voltage levels to be compared by said comparing means in response to the conductions of said driving circuits to produce a hysterisis between the upshift and downshift for the same gear shift.
 3. A control device according to claim 1, further comprising a gate circuit for permitting said any signal to flow only toward said comparing means.
 4. A control device according to claim 1, further comprising relay means for producing at its terminal the highest speed signal when actuated, a driving circuit for actuating the last-named relay means when rendered conductive, a logic circuit for rendering the last-named driving circuit only when said at least one driving circuit is kept inconductive, and a gate circuit for prohibiting said at least one driving circuit from being conductive. 